How do you solve #-2k^2=-162#?

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Answer 1 · 2016-08-18T11:33:23

#k = -2, or k= +2#

In solving a quadratic equation we usually make it = 0. However, in this case there is no term #x#, so we can use it in this form.

Isolate the variable.

#-2k^2 = -162 " "div -2#

#k^2 = 81" find square root"#

#k = +-sqrt81#

#k = 9 or k = -9#

Another method....

#-2k^2 +162 =0 " "div -2#

#k^2 - 81= 0" factorise"#

#(k+2)(k-2) = 0#
Each factor can be 0.

#k = -2, or k= +2#